b'Multiaxial Failure Envelopes and Uncertainty Quantification of Nuclear-Grade SiCf/SiCm Woven Ceramic Matrix Tubular CompositesPrincipal Investigator: Ghatu SubhashTeam Members/ Collaborator: Bhavani Sankar (Co-Pi, University of Florida (UF), Nam-Ho Kim (Co-PI, UF), Nance James (former UF student, currently at Sandia National Laboratories, New Mexico), Hemanth Thandaga Nagaraju (current UF PhD student), Christian Deck (Collaborator, General Atomics (GA)) and Sarah Oswald (Collaborator, GA)This research directlyS ilicon carbide (SiC) fiber- in fiber diameter, braid angle, reinforced ceramic matrixwall thickness of the tube, and (SiCf/SiCm) composite tubesporosity has been experimentally addresses theare being considered for nuclear fuelmeasured and a micromechanical uncertainty arisingcladding. However, their micro- model was developed to estimate from manufacturingstructure is highly heterogenousthe uncertainty in modulus and process by not onlyconsisting of fibers of differentstrength of the woven composites. developing multi-axialdiameters, braids woven at slightlyWe have utilized finite elementfailure criteria fordifferent angles, porosity of various(FE) based micromechanics to SiCf/SiC tubes undersizes, wall thickness variations anddevelop constitutive models for complex stress states,such. These variabilities introducewoven composites and determined but also providesuncertainty in mechanical propertiesthe failure envelopes under failure envelopesand failure strengths, even whenmultiaxial loading using thefor any combinationthe tubes are manufactured underDirect Micromechanics Method of loads and anominally same conditions. Hence(DMM). Concurrently, the phenomenologicalthe technical objectives of thecomposite tubes were tested failure criterionresearch were to quantify statisticalunder flexure, compression, and which can be easilyvariability in the prominent prop- hoop loading to determine their applied for designerties in SiCf/SiCm composites,failure strengths. Analyses was optimization by theexperimentally determine failurethen performed to propagate industry without thestrengths under various combina- uncertainties in the material need for interpolationtion of loads, develop constitutiveproperties and strength to establish or extrapolation fromrelations and failure envelopesvariability in failure envelopes limited experimentalfor complex multiaxial loadingunder multiaxial loading. Finally, data (i.e., the procedureconditions, and propose a phenom- the failure envelopes were validated developed here can beenological failure criterion which isusing a variety of experiments at used as an analyticaleasily adoptable in industry. static and dynamic strain rates laboratory that canin addition to experimental data replace the actual testingProject Description: available in the literature for the and thereby savingThe proposal aims to quantifySiCf/SiCm composites.considerable amount ofthe uncertainty (or variability) time and money). in properties (Elastic moduliFor safe design of nuclear reactors, and strength) of SiCf/SiCmuncertainty in properties and failure woven composite tubes arisingbehavior in all possible scenarios from the heterogeneity in theirmust be quantified. However, microstructural variables andinvestigation of failure behavior geometrical features. The variabilityunder such complex scenarios is cost 56 2022|AFC ACCOMPLISHMENTS'